Re: [PATCH v6 01/11] fuse: support copying large folios

[Joanne Koong <joannelkoong@xxxxxxxxx>]

On Thu, May 15, 2025 at 1:26 AM Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
>
> On Wed, 14 May 2025 at 02:18, Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
> >
> > On Mon, May 12, 2025 at 03:58:30PM -0700, Joanne Koong wrote:
> > > @@ -1126,22 +1127,22 @@ static int fuse_copy_page(struct fuse_copy_state *cs, struct page **pagep,
> > >                                       return err;
> > >                       }
> > >               }
> > > -             if (page) {
> > > -                     void *mapaddr = kmap_local_page(page);
> > > -                     void *buf = mapaddr + offset;
> > > +             if (folio) {
> > > +                     void *mapaddr = kmap_local_folio(folio, offset);
> > > +                     void *buf = mapaddr;
> > >                       offset += fuse_copy_do(cs, &buf, &count);
> > >                       kunmap_local(mapaddr);
>
> Fixed version pushed.

I think this needs to be:

                if (folio) {
                        void *mapaddr = kmap_local_folio(folio, offset);
                        void *buf = mapaddr;
                        unsigned copy = count;
                        unsigned bytes_copied;

                        if (folio_test_highmem(folio) && count >
PAGE_SIZE - offset_in_page(offset))
                                copy = PAGE_SIZE - offset_in_page(offset);

                        bytes_copied = fuse_copy_do(cs, &buf, &copy);
                        kunmap_local(mapaddr);
                        offset += bytes_copied;
                        count -= bytes_copied;

else it will only copy the first page of the highmem folio.

Thanks,
Joanne

>
> Thanks,
> Miklos